You know, you can become the leader of the guilds so fast because that's not in the focus anymore like before, it's not the "end of the path" where there's nothing to do after...
Technically it is not the end in the sense that you will get more quests, but upon finishing a guild line there is nothing more. You are treated exactly as you were prior to being the head of the guild and you still get the FEDEX quests.
For example, head of companions guild, what do i do now, oh talk to the other leaders of the guild and they tell me to go and bully someone. Please. That is 5 year old writing level.
New Vegas had some good stories and interesting characters in it. Far richer than skyrim. It is just not the case that you cant have good stories in open world games. In fact i wouldnt mind seeing a game where i am not the centre of everything, why not have other 'heroes' of the world, adventurers, that are also doing things. If they beat you to a quest then so be it. becoming the head of the guild should be a challenge and should have various perks that come with it. It shouldnt be a couple of fedex quests, and a couple of dungeon crawls, then bam "i know you only joined the mages guild a week ago, but you should run the place". Please it makes no sense and is not satisfying whatsoever